1. Field of the Invention
The present invention provides a novel crystalline material Si.sub.x C.sub.y N.sub.z possessing a direct optical band gap of 3.8 eV. Many optoelectronic applications, such as blue light emitting diode and laser diode, may utilize this property.
2. Description of the Prior Art
Although Si (indirect optical band gap of 1.1 eV) and GaAs (direct optical band gap of 1.45 eV) have been widely accepted today as basic semiconductor materials for fabrication of a large variety of electronic devices, the inability to tailor their optical band gaps prevents these materials being used for many other applications, especially those requiring high band gaps. The most outstanding example of such application is the fabrication of semiconductor Light Emitting Diodes (LEDs) and Lasers, spanning the whole visible range (1.8 eV to 4.0 eV). The materials to be used as lasers and LEDs necessarily require a direct optical band gap of appropriate energy, for efficient conversion of electrical energy into light energy. Notably, several semiconductor materials with direct band gaps between 1.45 eV to 2.8 eV have been developed, and have already been put into commercial applications, nevertheless, suitable semiconductor materials with direct band gap above 3.0 eV have yet to be commercialized. It has therefore been a major research area in the field of material science to develop materials with optical band gaps of larger than 3.0 eV. Towards this end, GaN as well as its alloys such as AlGaN and InGaN have exhibited great promise. However, commercial production of electronic devices based on these materials has still not been possible, owing to the several problems associated with these materials. It is therefore believed to be still pertinent to explore new materials for applications requiring high optical band gaps.